A method of and a loom for producing a tape having a list with laterally protruding loops

ABSTRACT

A method and a needle loom for producing a tape having a list with protruding loops along the edge at which is inserted the weft needle. An auxiliary sheet is superposed over one of the warp sheets and moves therewith;between these sheets there is inserted, in a direction opposite to the weft, double picks of a list thread with the heads thereof being held externally of the tape during weaving of the latter. The loom comprises a free needle disposed alongside the above-mentioned tape edge: the head of this free needle engages the double pick list heads and its shank allows them to slip off as the tape moves forward. The list is a double thickness fabric with intermediate links, in which is held the list thread forming the protruding loops. The tape can in particular be used to form a sliding clasp fastener: the list thread is then stiff and the heads of the protruding loops are then deformed to form the hooking elements of the fastener.

United States Patent Auer et al.

154] A METHOD OF AND A LOOM FOR PRODUCING A TAPE HAVING A LIST WITH LATERALLY PROTRUDING LOOPS [72] Inventors: Ulrich W. Auer, Chene-Bougeries/GE; Andre Nicole, Puplinge/GE,

both of Switzerland [73 Assignee: Interbrev S.A., Luxembourg, Luxembourg [22] Filed: Sept. 23, 1970 1] Appl. No.: 74,744

[151 3,692,068 [451 Sept. 19, 1972 OTHER PUBLICATIONS l;67;578-German Publication by Gollurg 4-1964.

Primary Examiner-Henry S. Jaudon Att0rney-Karl F. Ross [57] ABSTRACT A method and a needle loom for producing a tape having a list with protruding loops along the edge at which is inserted the weft needle. An auxiliary sheet is superposed over one of the warp sheets and moves therewith;between these sheets there is inserted, in a direction opposite to the weft, double picks of a list thread with the heads thereof being held externally of the tape during weaving of the latter. The loom comprises a free needle disposed alongside the above-mentioned tape edge: the head of this free needle engages the double pick list heads and its shank allows them to slip off as the tape moves forward. The list is a double thickness fabric with intermediate links, in which is held the list thread forming the protruding loops. The tape can in particular be used to form a sliding clasp fastener: the list thread is then stiff and the heads of the protruding loops are then deformed to form the hooking elements of the fastener.

28 Claims, 28 Drawing Figures PATENTEUSEPIQIBYE 3,692,068

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lNvE NTORS UL RICH W. AUEA ANDRE /V/COLE ATTORNEY METHOD OF AND A LOOM FOR PRODUCING A TAPE HAVING A LIST WITH LATERALLY PROTRUDING LOOPS FIELD OF THE INVENTION This invention relates to the manufacture, with a needle loom, of a tape provided along one of its edges with a list having protruding loops.

BACKGROUND OF THE INVENTION For the manufacture of tapes, a needle loom has several advantages over a shuttle weaving loom. However, the needle weaving loom also has a few drawbacks, in particular when it is used to manufacture a tape having a list with protruding loops that are formed by the weft thread, since these loops can only be produced along that one of the tape edges at which the needle inserts the weft picks, and provided resort is had to a pseudo warp thread, consisting of an auxiliary thread, of metal or of synthetic material, of limited length which, at one of its ends, is secured to a point of the loom that compels this end to follow one of the warp thread sheets in its shed-forming movements and which, at its other end, is trapped in the weave over a short length. This other end progressively extracts itself from the fabric as the tape moves forward, and thus releases the weft loops, which loops form the protruding loops. It is not possible by this means to form loops along the other edge of the tape, i.e., along the edge opposite to that at which the needle enters, because along this opposite edge the weft picks must be linked to one another by any suitable means, in particular means similar to those used in sewing machines to hold the sewing thread along the side of the material remote from the needle in, for example, formation of a chain stitch, auxiliary retaining thread, etc. This linking is necessary to enable the last warp thread to'b'e entwined by the weft to prevent it from escaping out of the fabric.

OBJECT OF THE INVENTION One object of the present invention is to provide a method for the manufacture of a tope with protruding loops in which these loops are formed, by means of an auxiliary weft needle, along that one of the tape edges which is opposite to the edge at which this auxiliary weft needle enters.

SUMMARY OF THE INVENTION The method provided by the present invention comprises superposing, over at least a part (at the weft pick insertion side) of one of the two main sheets of warp threads that are necessary for the weaving of said tape, an auxiliary sheet consisting of auxiliary warp threads, compelling this auxiliary sheet to follow the shed forming movements made by this main sheet during weaving, inserting, at least during some of these shed forming movements, a list thread into the space lying between this main sheet and the auxiliary sheet, such insertion being performed by an auxiliary needle, in the manner of a double pick and in a direction opposite to that of the double picks of the tape weft, retaining externally of the sheets (at the side of the tape edge) the heads of the list double picks thus formed, and releasing these list double pick heads upon completion of several shed-forming movements after this insertion, whereby these list double pick heads may form, once released, said protruding loops.

This method in particular enables the manufacture of a tape with protruding loops for use as one of the two halves of a sliding clasp fastener. In such a case, use is made of a list thread which includes a deformable material at least in those portions thereof that are intended to form the protruding loops, which material is subjected to local deformation in the region of the loop heads, thereby to provide the list thread with a crosssection such as to enable the protruding loops to come into hooking interengagement with the protruding loops of an identical tape forming the other half of the sliding clasp fastener.

The invention also provides a needle loom for manufacturing a tape having a list with protruding loops, which comprises a weft needle associated with a hook for inserting, in the form of double picks and between two main sheets of warp threads, the weft thread of the tape. An auxiliary needle is provided for inserting, in the form of double picks, a list thread into a space between one of the main sheets and an auxiliary sheet consisting of auxiliary warp threads overlying at least part of the warp threads of this main sheet from the side at which are inserted the weft thread double picks. The auxiliary sheet is caused to follow the shed-forming movements of said one main sheet, while retaining means is enclosed for retaining the heads of the list thread double picks. The retaining means includes a free needle disposed parallel to the tape side which is remote from the location at which the auxiliary needle enters said space, which free needle is adapted to be entwined by the heads of the list thread double picks to retain them in a transverse direction outside the tape and to enable them to slide longitudinally over the needle while moving with the'tape. We also make use of maintaining means able to hold the free needle in the same position before each entwinement by the list double pick heads. When this loom is intended to manufacture a tape for a sliding clasp fastener, it moreover comprises means able to produce in the cross-section of the list thread, at those places where the latter forms the heads of the protruding loops, a permanent deformation which broadens this cross-section in a direction parallel to the longitudinal axis of the tape, thereby forming the protruding loops with the required shape for them to act as hooking elements in a sliding clasp fastener.

The resulting product is a tape having a list with protruding loops, comprising a tape body and a list in which is trapped a spirally arranged list thread with the leading ends of the turns thereof projecting from the outer edge of the list and constituting the protruding loops. The tape body has a fabric structure of single thickness formed by the entwinement of a double pick weft with warp threads. The said list has a fabric structure of double thickness with intermediate links which includes a lower strata formed by the entwinement of a first series of double picks of the weft with a first series of warp threads. The lower strata is disposed to one side of the spiral and constitutes one of the surfaces of the list. An upper strata is formed by the entwinement of a second series of double picks of said weft with a series of auxiliary warp threads and a second series of warp threads, the second layer being located to the other the of said spiral and constituting the opposite surface of the list. Intermediate links are formed by the traversing portions of the second series double picks and by the traversing portions of the second series warp threads, the traversing portions passing from one strata to the other and being disposed between the consecutive turns of the spiral so as to be entwined by the trailing ends of the spiral turns.

When this tape is intended for use as one half of a sliding clasp fastener, the list thread includes a deformable material at least in the portions thereof that form turns, and the cross-section of the list thread is deformed at the apexes of the heads of the turns so as to enable these turns to interengage with the corresponding turns of a second tape constituting the other half of this sliding clasp fastener.

DESCRIPTION OF THE DRAWING The following description relates to a preferred method, to two examples of the needle loom and to an example of the tape provided by the present invention. It is illustrated by the following accompanying drawing in which:

FIG. 1 is a diagram explaining the method,

FIG. 1A is a detail view illustrating an aspect of the invention,

FIGS. 2 and 3 are simplified side and plan views respectively, of part of this particular needle loom,

FIG. 4 is a plan view, on a large scale, of the tape manufactured by the loom shown in FIGS. 2 and 3,

FIGS. 5, 6 and 7 are views of a first variant of a particular element of the loom visible in FIGS. 2 and 3, FIGS. 5 and 6 being plan views and FIG. 7 being a section along line VIIVII of FIG. 6,

FIGS. 8 and 9 are views of second variant of this particular element, FIG. 8 being a plan view and FIG. 9 being a section along line IXIX of FIG. 8,

FIGS. 10 and 11 are views of a third variant of this same particular element, FIG. 10 being a plan view and FIG. 1 1 being a section along line XI-XI of FIG. 10,

FIGS. 12 and 13 relate to an example of the sliding clasp tape resulting from the application of the method, FIG. 13 being a side view and FIG. 13 being a plan view,

FIG. 14 is a section along line XIV-XIV of FIG. 13,

FIG. 15 represents a plan view, as well as cross-section of part of a fourth variant of the particular element visible in FIGS. 2 and 3, this fourth variant being more particularly intended to the application of the method,

FIGS. 16 to 21 represent various examples of the form that another particular element may take for this application,

FIGS. 22 to 24 represent, viewed in plan, three examples of an auxiliary member which the loom visible in FIGS. 2 and 3 may comprise for the application of the method,

FIG. 25 is a detailed diagrammatic perspective view, with parts broken away, showing the structure of the resulting tape, and

FIGS. 26 and 27 are respectively a diagrammatic cross-section and a diagrammatic longitudinal section of the fabric illustrated in FIG. 25, which sections are taken along the directions indicated by arrows A and B respectively.

SPECIFIC DESCRIPTION The method forming the subject of the invention is diagrammatically illustrated in FIG. 1 In this Figure may be seen the two main sheets 1 and 2 in which are distributed the warp threads 3. It has been supposed, in this diagram, that the warp threads belong alternately to the two sheets, with the odd ranking threads, such as the threads 3 3 3 belonging to sheet 1 and the even ranking threads, such as the threads 3 3 3 belonging to sheet 2. The weft of the tape is formed by double picks, such as the double pick 4, whose head 5 delimits the two strands 4, and 4 These double picks are inserted from the edge 6 of the tape, in the direction indicated by arrow 7. Above the sheet 2 there is an auxiliary, so-called list, sheet 9 consisting of auxiliary warp threads 8 8 8, which lie in superposed relation to the threads 3 3,,,..., 3, of the main sheet 2 and directly over the latter, which threads are located towards the side of the edge 6 of tape 10 at which the insertion of the double picks 4 takes place.

This list sheet 9 keeps, in relation to the main sheet 2, an invariable relative position, and it follows the shed forming movements made by the latter during weaving of the tape. At certain shed forming movements, e.g., at every second such movement, there is inserted into the space lying between the sheets 2 and 9 two strands of an auxiliary, so-called list, thread that are connected by a loop, as can be seen in FIG. 1 in regard to the two strands 11 and 11 that are connected by the loop 12. This loop 12 constitutes the head of the pair 11 formed by the two strands 11 and 11 The insertion of this pair 11 is done in the manner of a double pick and that is why this pair will henceforth be termed list (thread) double pick, although the list thread behaves within the woven tape like a warp thread having a zig-zagging lay and not as a weft thread. The insertion of the list double pick takes place in a direction 13 which is opposite to the direction of insertion 7 for the double pick 4 of the tape weft. The head 12 of this list double pick 11 is held outside the sheets 2 and 9 and at least until the completion of several shed forming movements subsequent to such insertion; the head is then released. The heads of these double picks 11, once released, form the list loops 15 that protrude from the edge 6 of the list 16 of tape 10.

The above describes the very simple case where the warp threads 3 are distributed in order of parity between the two main sheets 1 and 2; but obviously the warp threads can be distributed in any other way. Also, the width of the list 16 is arbitrary: in an extreme case, this list could extend up to the edge 17 opposite to that from which protrude the loops 15. Finally, the law of alternation with which the double picks 4 of the weft and the double picks 11 formed by the list thread (in the described example, there is inserted one list double pick for every two insertions of weft double picks) can be chosen at will in dependence on the most diverse criteria: intended use of the tape, desired decorative effect, toughness and aspect of the list, etc.

For obtaining separation of the main warp sheet 2 from the superposed auxiliary warp sheet 9 (FIG. I), use can be made of special heddle bars such as the bar 151 (FIG. 1A) provided with two eyelets 152 and 153, the lower eyelet 152 guiding a thread 154 belonging to the warp main sheet 2 of FIG. 1 and the upper eyelet 153 guiding a thread 155 belonging to the auxiliary warp sheet 9 of FIG. 1. Other convential heddle bars, such as the bar 156, with a single eyelet 157, guide the threads (e.g. the thread 158) belonging to the other main warp sheet (bearing the reference 1 in FIG. 1). Conventional means, not shown, are further provided for imparting to all double-eyelet heddle bars 151 and to all single-eyelet heddle bars 156 the usual oppositely alternating shed-forming movements indicated by the full and interrupted arrows 159, 160 and 161, 162 respectively. FIG. 1A also shows the weft thread 163 that is inserted in a direction away from the observer (as depicted by the arrow 164 seen from the rear), thus forming a double pick with a head 165, and further shows the list thread 166 that is inserted in a direction towards the observer (as indicated by the arrow 167 seen from the front), thus forming a double pick with a head 168. The first double-eyelet heddle bar 169 guides a single warp thread 170 bordering the list and the first single-eyelet heddle bar 171 guides a warp thread 172 bordering the tape. These two bordering warp threads are subjected to a greater tension than the others, as is apparent from FIG. 1A, in order for them to firmly encompass the protruding loops 173 constituted by the heads of the list thread double picks, which heads are kept outside the tape list by means described further on.

As for the machine for carrying out the described method, it consists of a needle loom of conventional type to which modifications have been made as will now be described, with reference to FIGS. 2 and 3, in which are to be seen the framework 20 carrying the support 21 on which is mounted the tape guide 22. The needle 24 is the usual needle which, in any loom of this type, serves to insert the double pick weft. A known mechanism, not shown, periodically moves this needle so that it engages in the hook 27 the head of the double pick that its eye 25 inserts into the shed opening. This hook 27 moves longitudinally, under the action of a mechanism not shown, so as to form the selvedge crocheting that forms the edge of the tape 23. These elements exist in any needle loom and are will known, so that there is no need to describe them in greater detail here.

The modification which forms the subject of the invention first consists in the presence of an auxiliary needle 28 for inserting the list thread. This auxiliary needle 28 is carried by a vertical shaft 29 which pivots about its axis 30 under the action of a drive mechanism, not shown, which causes the list needle 28 to move from its rest position, shown in full lines, to its insertion position, shown by the broken line outline 28'.

The modification moreover consists in the presence of a so-called free needle 31 which in this example has the appearance of a hook. This hook is positioned parallel to the tape edge along which the list 32 with protruding loops is to be formed. This hook is free in so far as it is not secured to any part of the machine there is merely an abutment 33 which cooperates with its nose 34 for the support thereof, this abutment being provided with a slot 35 in which the nose engages. The shank 36 of the free needle is kept in place by the heads of the list double picks that have been inserted in the course of the previous stages of the weaving operation.

The abutment 33 is secured to the end of a sliding rod 37 and has imparted thereto a small reciprocatory movement parallel to the edge of the list 32 each time the needle 28 completes its movement of insertion; the amplitude of this movement is just sufficient to disengage the nose 34 whereby the head of the list double pick may come and entwine it. This rearward motion is brought about by a mechanism consisting of a lever which pivots about a pin 39 and of which one arm 40 is actuated by a rotary cam 42 which is formed with a flat 43 and which is mounted on a shaft 44 driven by any suitable means, not shown. A spring 45 exerts a pull on the other arm 41 of the lever, thereby to keep the arm 40 in contact with the cam 42.

The operation of this machine will be clearer if reference is made to FIG. 4, which shows a plan view of the tape 23 during formation, at the instant when a double pick 4 of the weft is being inserted by the needle 24 into the shed opening (between the main warp sheets 1 and 2 of FIG. 1) at the same time as a double pick 11 of the list thread is being inserted by the auxiliary needle 28 beneath the auxiliary warp sheet 9, between the latter and the main sheet 2. The head of the double pick 4 is brought into engagement with the nose of the selvedge crocheting hook 27, while the head 12 of the double pick 11 of the list thread is brought into engagement with the nose 34 of the free needle 31, the abutment 33 (FIGS. 2, 3) being located in its withdrawn position in which it has released the nose 34. At the instant when the auxiliary needle 28 moves back to its rest position, the tension exerted by the list thread feeding system (not shown) causes the head 12 of the double pick 11 to slip under the nose 34 of the free needle 31 and to form a loop similar to loop 15. The abutment 33 then returns to the position shown in FIGS. 2 and 3 and prevents the free needle 31 from being entrained with the tape 23 travelling in direction 46 it is the protruding loops that slide along the shank 36 of the free needle 31 and which progressively free themselves from it by slipping off its end 47. During that time, the weft needle 24 (which inserts the weft of the tape) is withdrawn also, and the selvedge crocheting hook 27 carries out the known movement that leads to the formation of the crocheting 18.

It will be observed that one of the essential components of the needle weaving loom carrying out the method provided by the invention is the free needle 31. In the above described example (this example refers to a loom manufacturing a single tape, but it is clear that a loom manufacturing several tapes would include one auxiliary needle 28 and one free needle 31 per tape), this free needle has the appearance of a stem 36 (which forms the shank thereof) provided with a nose 34 (which forms the head thereof). This, however, is only one particular form, and many variants are possible.

Thus the head could have the form of a butt 51 (FIGS. 5, 6 and 7) that is delimited, along the side opposite to the tape, by a concave outline 52. This butt can possibly be provided with one, or even two bosses 53, 54 (FIGS. 6 and 7) to facilitate cooperation thereof with the abutment 33 discussed in connection with reference to FIGS. 2 and 3; in that case, the abutment can assume the form of a yoke as indicated diagrammatically by the outline in broken lines 55 visible in FIG. 6.

The head may also consist of a spheroidal swelling 56 (FIGS. 8 and 9) that is fixed to the shank in an eccentric position in relation to the latter, the off-setting being directed away from to the tape; this spheroidal swelling cooperates with the abutment, the latter having a shape adapted to this type of head.

The head may further have the form of a nail head 58 (FIGS. 10 and 11 of which the portion 59 adjacent the tape has been struck down.

In each of these types of free needle, the connecting ridges have been rounded or even completely done away with so as to prevent the list thread from being damaged when it entwines the needle head and slides along its shank.

Numerous other free needle variants can be imagined and it would not be appropriate to give here an exhaustive list. In all of these variants, the head has a dual function firstly, it facilitates the entwining of the free needle by the list thread and secondly, it cooperates with the abutment. In all cases, this head constitutes a protuberance located at one of the ends of the needle and directed away from the tape, and this protuberance must be located in alignment with the shed opening whereas its shank lies along the edge of the list.

In some cases, the free needle can even not have a head in the true sense of the word it suffices that the needle have a cross-section that decreases from one end to the other, the law governing the decrease being so chosen that the tension exerted on the list thread has a longitudinal component sufficient to cause the needle to slide at each beating up motion of the comb 38 (see. FIG. 2) in a direction opposite to the advancing movement of the tape, the sliding movement of the free needle in relation to the loops being of the extent necessary to compensate the advancing movement of the tape, so that, by virtue of this reversible wedge effect, the free needle finally retains an unchanging position in relation to the loom. An arrangement as simple as this, which avoids having to resort to an abutment to prevent the free needle from being entrained by the tape, can only be used in the relatively few cases where the value of the tension exerted on the list thread and where the value of the frictional coefficient between the materials from which the list thread and the needle are made enable it to. In most cases, however, it is not possible to avoid resorting to an abutment.

The free needle is not necessarily rectilinear in particular, the head can be slightly offset upwards in relation to the shank, as is the case with the nose 34 of the free needle 31 shown in FIG. 2.

The material used to make the free needle is of no importance, provided it can resist the stresses exerted by the tension of the list thread the most usual is for it to be made of metal, of wood or of a synthetic material.

In the example illustrated in FIGS. 2 and 3, the abutment is a movable abutment which performs a reciprocatory movement for the purpose of freeing the head, at least at the instant when the list thread must entwine the latter (at the end of the movement of insertion performed by the auxiliary needle), and to put the needle pack in place, by causing it to slide longitudinally in relation to the loops already formed, so as to prevent it from being progressively entrained by the tape.

In view of the fact that the head of the free needle can, because of the off-center position of its center of gravity, have a tendency to droop by causing the needle to rotate about its longitudinal axis, the abutment moreover serves to put the head back in position in the vertical sense by causing the free needle to perform a reverse rotary motion about its axis such as to compensate the first.

However, the abutment can also be stationary. It suffices that it be endowed with a resiliency such as to enable the list thread, at the instant when the latter entwines the head of the free needle, to move it away whereby the loop that the thread forms may slide towards the shank of the free needle, which resiliency causes the abutment to return to its initial position so that it can exercise on the heat of the free needle its dual anti-entrainment and anti-rotation effect.

It will be observed that the abutment, whether it be movable or stationary, constitutes a maintaining means capable of maintaining the free needle in the same position before each entwinement by the heads of the list thread picks.

As has been explained earlier, the cross-section of the shank can vary along the latter. This variation can affect either the area or the shape of the crosssection, or both together. The main purpose of a change in area is to facilitate the sliding motion of the loops, whereas a change in shape can be used to impart to the loops a particular configuration, for example with a view to providing the tape with a particular decorative aspect or a special technical effect. These variations in area and/or shape can be continuous or discontinuous.

We shall now describe an example in which a continuous variation in the shape of the cross-section is put to use for manufacturing a tape intended to constitute one of the two parts of a sliding clasp fastener, whose hooking elements are formed by the protruding loops made by the method analyzed above. In this application, use is made for the list thread of a thread formed, at least partly, of a deformable material, e.g., nylon. In the following example, it will be supposed that this thread is a homogeneous monostrand or monotilament. The list of the tape is manufactured in the manner described earlier to produce the protruding loops. Once the loops are formed, the cross-section of the monostrand constituting them is deformed to produce at the apexes of the loop thickenings of this cross-section, which thickenings are oriented along a longitudinal axis parallel to the edge of the list. This is what is shown in FIGS. 12 and 13 in which are to be seen the circular cross-section 65 of the monostrand 66 constituting the list thread, and the thickenings 67 and 68 that are formed at the apexes 69 of the protruding loops 70 in a direction parallel to the longitudinal axis 71 of the list 16. To produce these thickenings by deformation, various methods can be used. Use can in particular be made of a free needle whose shank is shaped, over at least part of its length, like a bevel. This is what is shown in FIGS. 13 and 14 where the shank of the free needle 31 is seen to have a cross-section 75 which is elongated towards the outside of the list 16, this cross-section being delimited by two lateral surfaces 76, 77 which meet along a rounded ridge 78 constituting the apex of the bevel. The fact of using a free needle bevelled in this way results in a decrease of the radius of curvature of the support on which the loops are formed and hence in an increase of the stresses to which the material constituting the monostrand is subjected at that location, to the point that these stresses exceed the elastic limit of this material, which becomes crushed to give rise to the thickenings 67, 68. The stresses to which the material of the monostrand is subjected can be increased by resorting to a free needle whose shank has a cross-section that varies from point to point, as is apparent from FIG. 15. In this Figure it will be observed that, starting from the head of the free needle, which head is supposed to be located to the left, the shank 36 first has a circular cross-section A, then it is flattened and has a substantially rectangular crosssection B; it is then bevelled, its cross-section having a shape C which is reminiscent of the cross-section 75 in FIG. 14, but the height h is greater than the height h of cross-section B, thus giving rise to a bulge 79 in the bevelled part of the shank. From this bulge, the height h, of section D returns to the value h,, h,, that it had at B. The shank then becomes progressively thinner, with the area of its cross-section gradually decreasing, and ends in a tip 80 of circular cross-section F. This example, which illustrates one possibility for achieving the deformation of the protruding loops that is necessary to enable the tape to be used as part of a sliding clasp fastener, shows also that the shank of the free needle may have diverse forms, in particular that its cross-section may vary both as regards its shape and its area.

Inthe above example of embodiment of a tape intended to form part of a sliding clasp fastener, it has been assumed that the list thread was made up of a homogeneous monostrand of a deformable material. But other kinds of threads could come into the reckoning, in particular (FIG. 16) an ordinary textile thread 82 coated with a circumferential layer 83 of deformable material forming a sheath around the thread, or (FIG. 17) an ordinary textile thread 82 which is partly covered over, i.e., only over part of its cross-section, with a longitudinal layer 83 of deformable material. The thread 82, which constitutes as it were the core of the list thread, can be replaced by a filiform element other than textile, e.g., by a metallic cord or by metallic monostrand. The cross-section of the list thread can also be other than circular this is already apparent from FIG. 17 where the contour 84 of its cross-section is ovoid, but one could also take a flat list thread, having a cross-section of substantially rectangular contour, whether the core 85 of textile, metallic or other material of this thread be itself flat (FIG. 18), or whether only the deformable material coating 86 has a substantially rectangular contour, with the core 85 being circular (FIG. 19). The deformable material coating, whether circumferential (as in FIG. 16) or partial (as in FIG. 17), may be continuous, i.e., extend over the entire length of the thread, or be discontinuous, i.e., only exist at those locations of the thread that will give rise to protruding loops (see FIGS. 20 and 21). The list thread may also be hollow and assume the form of a tube, whether of metal or of deformable material. It can finally bepre-marked, i.e., be provided beforehand with local deformations located at positions that will coincide with the apexes of the loops onceit has been put in place in the list, these local deformations constituting either primers for the deformations that will turn these protruding loops into the hooking elements, or constituting the final deformations themselves.

In general, the list thread must be made, either wholly or in part as explained above, of a material which is at the same time sufficiently flexible to form the loops, sufficiently deformable, in the case of a sliding clasp fastener tape, for its cross-section to be deformed at the apexes of the loop heads for the loops to form the hooking elements of such a fastener, and sufficiently rigid to enable these hooking elements once formed to fulfill their function in a fastener. The choice of material must therefore be the result of a compromise between the required properties of flexibility, deformability and rigidity, and this compromise depends moreover on the transverse structure of the thread, which can be either homogeneous (solid monostrand, or tubular monostrand) or heterogeneous (sheathed thread, or reinforced" thread with a single stranded core, whether metallicor not, or with a multiple stranded core, whether made of textile fibers, of a metal or some other suitable material and whether twisted or not).

The deformation of the cross-section of the protruding loops may be facilitated by auxiliary external means. Thus, as can be seen from FIG. 22, there can be fitted to the loom a crushing member 48 having a'ramp 49 for progressively crushing the heads 69 of the protruding loops 70 againstthe shank 36 of the free needle, as they come to slide over the latter under the effect of the tapes motion. This crushing member can for instance be secured to the tape guide 22.

Resort may also be had to a hammer which carries out a crushing action by repeated impacts on the heads of the protruding loops while they travel along. the shank of the free needle, which thus acts an anvil.

These are auxiliary means which are purely mechanically acting. Resort may also be had to auxiliary means which are thermally acting by heating the heads of the protruding loops, which heating, by softening the material used to make the list thread, facilitates the cross-sectional deformation imposed by the outline of the needle shank. This heating can be done very simply by fitting the loom with a nozzle 88 which projects on to the heads of the loops a jet of hot air 89. The abovementioned mechanical and thermal means can be combined; there are various ways in which this could be done and which it would be pointless to describe in detail here.

There exists however a particular means that combines the mechanical and thermal effects and that is to use vibration of high frequency, in particular of ultrasonic frequency. Such ultra-sonic vibration is applied by means of a, for instance piezo-electric, transducer, which presses the apexes of the loops against the shank 36 of the free needle. It is this means that is illustrated in FIG. 24. The ultra-sonictransducer comprises a solid body 90 in which is housed the piezo-electric system and a vibrations concentrator 91 of which the tip 92 comes into contact with the apexes 69 of the loops 70, while the latter travel along the shank 36 of the free needle. It will be seen that this system combines a mechanical effect (high frequency hammering due'to the vibration) and a thermal effect (heating due to the absorption of the ultra-sonic vibration within the material of which the list thread is made).

As for the tape that is produced by the method described above, its structure is diagrammatically illustrated in detail in FIGS. 25 to 27, the list thread having tape body 101 is formed by the usual entwinement of warp threads 105 with double picks 106 and 107 of a weft thread. The list 102 (FIG. 26) is formed by a first entwinement 108, which involves the warp threads 109, 110, 111 and 112 and the weft double picks 106, and a second entwinement 113, which involves the warp threads 114, 115 and 116 and the weft double picks 107. The first entwinement 108 forms the bottom strata of the double thickness fabric and the second entwinement 113 forms the top strata thereof. Between these two stratas is trapped the flattened spiral 103. The thread forming the spiral 103 is none other than the list thread 11 to which reference was made in connection with FIG. 1, whereas the warp threads belonging to the top strata 113 of the list are those that form the auxiliary sheet 9 in FIG. 1; as for the warp threads belonging to the bottom strata 108, they are those forming the two main sheets 1 and 2. The warp threads belonging to the top strata 113 are more highly tensioned than the warp threads belonging to the bottom strata 108, thus compelling some of these latter threads, the threads 111 and the weft double picks 107 (i.e., those that are inserted between the list double pick insertions), to rise up to the level of the upper strata 113. As a result of this, the vertical portions 111a of the warp threads 111 and the vertical portions 107a and 107b of the double picks 107 constitute the intermediate links of the double thickness fabric forming the list. These vertical portions 1110 of the warp threads 111 and the vertical portions 107a and l07b of the weft double picks 107 moreover constitute spacing thicknesses with serve to separate consecutive turns of the spiral (e.g., turns 117 and 118) and to keep them equidistant from one another and oriented in parallel planes at right angles to the list (e.g., planes 117a and 118a in the case ofturns117 and 118); as for the vertical portions 107a of the double picks 107 (which double picks are entwined by the internal portions 119 of the spiral turns), they prevent the latter from escaping out of the fabric and consequently anchor the spiral 103 in the list 102. Moreover, the warp threads 114, 115 and 116 of the top strata 113, the outermost warp threads 109 and 112, which, in the bottom strata 108, delimit the list 102 widthwise (these threads belong to the main sheet 2 (FIG. 1) which is subjacent the auxiliary sheet 9), are subjected to a greater tension than the other warp threads 110 and 111 of this bottom strata thereby preventing any lateral displacement of the elements forming the list 102.

As stated earlier, such a tape can form one-half of a sliding clasp fastener provided the list thread has rigidity and provided the heads 104 of the spiral turns can be deformed so that they can come into hooking interengagement with the heads of the spiral of another, identical, tape. In such a case, the list thread can as sume, in addition to the various forms listed above, the

form of a thread made of a metal or of a metal alloy. It can thus consist of a bundle of monostrands made of synthetic material, of a metal or an alloy, whether twisted together or not. When the list thread assumes the form of a tube (tubular monostrand, which may be made of a synthetic material, of a metal or of a metal alloy), the tube may be filled with a material forming the core of this list thread; besides the cited case where the core is made of a textile thread or of a metal thread (the list thread is then a sheathed" thread), the core can also, in another case, be made of any soft material, other than textile.

Thus with the present invention tape for sliding clasp fasteners can be manufactured in a completely continuous manner, without being subjected to the limitations that are inherent to the known methods, which limitations consist either in the necessity of having to resort I to a pre-manufactured spiral, if this spiral is to be incorporated in the list while the tape is being woven, in the manner of a warp thread, or in the necessity of having to resort to a two-shuttle loom, if the spiral is to be manufactured from a filiform element which is formed into a spiral during weaving of the tape, one of the shuttles containing the weft thread and the other containing this filiform element, and this latter necessity has the effect of slowing down production because of the need of frequently having to reload the shuttles as the latter can only contain limited lengths of thread. The possibility of resorting to a two-needle loom, such as the one described above, is of considerable advantage since the thread for the spiral and the weft thread can be supplied in an uninterrupted manner; the rate of production can then reach very high values.

We claim:

1. In a method of manufacturing a tape by weaving a weft thread with warp threads distributed into two main warp sheets that are alternately inclined with respect to one another thus successively forming sheds into which the weft thread is introduced from a weft-picks insertion side in the form of weft-thread double picks, and providing said tape along one of its two longitudinal edges with a list having successive list-thread loops protruding laterally from this list, the improvement which comprises the steps of:

superposing an auxiliary sheet of auxiliary warp threads over at least a part of one of said main warp sheets located to the weft-picks insertion side;

constraining said auxiliary sheet to follow each shedforming movement executed by said one of said main warp sheet during weaving;

inserting at least during some of said shed-forming movements between said one main warp sheet and said auxiliary warp sheet, a list thread as a double pick constituted by two parallel portions of this list thread connected by a third portion forming a head of the double pick, each insertion being in a direction opposite to that of said weft-thread double picks;

retaining externally of the sheets said heads of the list-thread double picks; and

releasing these heads upon completion of several shed-forming movements after insertion of the listthread double pick whereby the said list-thread double pick heads form upon the protruding listthread loops.

2. The improvement defined in claim 1, further comprising the step of covering the list thread over the entire circumference of its cross-section with a layer of deformable material forming a sheath.

3. The improvement defined in claim 1, further comprising the step of providing said list thread over part of its cross-section with a layer of synthetic material forming a longitudinal bead.

4. The improvement defined in claim 1, further comprising the step of applying to said list thread a layer of deformable material only at those places which are intended to constitute said list pick heads.

5. The improvement defined in claim 1, further comprising the step of premarking said list thread by a deformation of its cross-section at locations constituting the listthread heads.

6. The improvement defined in claim 1, further com prising the step of filling said list thread in the form of a tube with a soft material.

7. The improvement defined in claim 1, further com prising the step of forming said list thread as a filiform element with a cross'section of periodically varying area and/or shape.

8. The improvement defined in claim 1 wherein said list thread is a filiform element which, at those places which are intended to constitute the list-thread double pick heads, is formed at least in part of a deformable material, and which comprises the further step of:

producing at the apexes of said list-thread double pick heads a permanent deformation of the filiform elements cross-section thereby to widen said cross-section in a direction parallel to the edge of the tape and to impart to said protruding loops the required shape for them to act as hooking elements in a sliding clasp fastener.

9. in a needle loom for manufacturing a tape having a list-thread provided with protruding loops and comprising means for separating the warp threads into two main sheets and for imparting to said sheets an alternate shed-forming movement, and a weft needle associated with a weft hook for inserting between said main sheets a weft thread in the form of double picks from a weft-thread insertion side, the improvement which comprises:

means for forming an auxiliary sheet consisting of auxiliary warp threads superposed over at least a part, located to the weft-thread insertion side, of one of said main sheets and for compelling this auxiliary sheet to follow the shed-forming move ment of this main sheet;

an auxiliary needle for inserting, from the side opposite to the weft-thread insertion side, a list thread into the space between said auxiliary sheet and its associated main sheet, thus forming listthread double picks; and

means for retaining the heads of the list thread double picks, said retaining means including a free needle disposed parallel to the tape side whichis remote from the location at which the auxiliary needle enters said space, said free needle having a position with respect to the trajectory of the auxiliary needle such as to allow the heads of said listthread double picks to entwine the free needle, thus being retained outside the tape in a transverse direction, and to slide longitudinally over the free needle while moving with the tape, said retaining means further including maintaining means able to hold the free needle in the same position before each entwinement by the list-thread double pick heads.

10. The improvement defined in claim 9 wherein the free needle comprises a head located in alignment with the shed and a shank located in alignment with the tape, said shank having a smaller cross-section than that of the head and said head being connected to the shank by rounded surfaces.

11. The improvement defined in claim 10 wherein said head has the form of a butt that is delimited, along the side remote from the tape, by a concave outline and, along the side adjacent the tape, by a rectilinear outline.

12. The improvement defined in claim 10 wherein said head has the form of a ball secured at the end of said shank in an eccentric position in relation to the longitudinal axis of the shank, the, offsetting being directed away from the tape.

13. The improvement defined in claim 10 wherein said head has the form of a nose that is curved away from the tape.

14. The improvement defined in claim 10 wherein said maintaining means include an abutment adapted to cooperate with said head so as to prevent it from rotating about its longitudinal axis and from being entrained longitudinally with the moving tape, thus holding said free needle in a given working position.

15. The improvement defined in claim 14 wherein said abutment is a movable abutment wherein means is provided for imparting thereto a reciprocatory movement in a direction parallel to the motion of the tape, said reciprocatory movement including a withdrawal phase, in the direction of said motion, during which the abutment releases said head, and an advancement phase, in a direction opposite to said motion, during which the abutment returns the head to its initial position, the withdrawal phase beginning with the entwinement of the free needle head by the list-thread pick head and the advancement phase beginning after such entwinement.

16. The improvement defined in claim 14 wherein said abutment is a stationary abutment endowed with the resiliency that is required to enable the head of the list-thread double pick inserted by the auxiliary needle to entwine the head of the free needle, by elastically moving the abutment away from said head.

17. The improvement defined in claim 10 wherein the shank of the free needle has the shape of a bevel, whose ridge is located to the side remote from the tape list.

18. The improvement defined in claim 10 wherein the shank of the free needle has a crosssection of which the shape varies along said shank.

19. The improvement defined in claim 10 wherein the shank of the free needle has a cross-section of which the area varies along said shank.

20. The improvement defined in claim 19 wherein the variation of said area is continuous.

21. The improvement defined in claim 19 wherein the variation of said area is discontinuous.

22. The improvement defined in claim 9 wherein said maintaining means consists in a variation of the shape and area of said cross-section, said variation imparting to the free needle the shape of a sharp wedge having a slope so chosen that the free needle may be subjected, under the action of the tension in the list-thread, to a longitudinal force capable of compensating the driving force to which it is subjected under the effect of the tape motion.

23. The improvement defined in claim 9, further comprising deforming means capable of producing, at the apexes of said list-thread double pick heads, a permanent deformation of the cross-section of the list thread, such deformation having the effect of broadening this cross-section in a direction parallel to the longitudinal axis of the tape whereby the tape may be utilizable as one of the halves of a sliding clasp fastener of which the hooking elements are formed by said protruding loops.

24. The improvement defined in claim 23 wherein said deforming means include a crushing member having a slope adapted to cause progressive crushing of said list-thread double pick heads against the shank of said free needle while they slide along the shank.

25. The improvement defined in claim 23 wherein said deforming means include a hammer adapted to crush said list-thread double pick heads against the shank of said free needle by hammering them while they slide along the shank.

26. The improvement defined in claim 23 wherein said deforming means include a heating device capable of locally heating said list-thread double pick heads while they slide along the shank of said free needle.

27. The improvement defined in claim 26 wherein said heating device includes a nozzle projecting a jet of hot air onto said list-thread double pick heads.

28. The improvement defined in claim 23 wherein said deforming means include a generator of ultrasonic vibrations adapted to irradiate with ultrasonic waves said list-thread double pick heads while they slide along the shank of said free needle. 

1. In a method of manufacturing a tape by weaving a weft thread with warp threads distributed into two main warp sheets that are alternately inclined with respect to one another thus successively forming sheds into which the weft thread is introduced from a weft-picks insertion side in the form of weftthread double picks, and providing said tape along one of its two longitudinal edges with a list having successive list-thread loops protruding laterally from this list, the improvement which comprises the steps of: superposing an auxiliary sheet of auxiliary warp threads over at least a part of one of said main warp sheets located to the weft-picks insertion side; constraining said auxiliary sheet to follow each shed-forming movement executed by said one of said main warp sheet during weaving; inserting at least during some of said shed-forming movements between said one main warp sheet and said auxiliary warp sheet, a list thread as a double pick constituted by two parallel portions of this list thread connected by a third portion forming a head of the double pick, each insertion being in a direction opposite to that of said weft-thread double picks; retaining externally of the sheets said heads of the list-thread double picks; and releasing these heads upon completion of several shed-forming movements after insertion of the list-thread double pick whereby the said list-thread double pick heads form upon the protruding list-thread loops.
 2. The improvement defined in claim 1, further comprising the step of covering the list thread over the entire circumference of its cross-section with a layer of deformable material forming a sheath.
 3. The improvement defined in claim 1, further comprising the step of providing said list thread over part of its cross-section with a layer of synthetic material forming a longitudinal bead.
 4. The improvement defined in claim 1, further comprising the step of applying to said list thread a layer of deformable material only at those places which are intended to constitute said list pick heads.
 5. The improvement defined in claim 1, further comprising the step of premarking said list thread by a deformation of its cross-section at locations constituting the list-thread heads.
 6. The improvement defined in claim 1, further comprising the step of filling said list thread in the form of a tube with a soft material.
 7. The improvement defined in claim 1, further comprising the step of forming said list thread as a filiform element with a cross-section of periodically varying area and/or shape.
 8. The improvement defined in claim 1 wherein said list thread is a filiform element which, at those places which are intended to constitute the list-thread double pick heads, is formed at least in part of a deformable material, and which comprises the further step of: producing at the apexes of said list-thread double pick heads a permanent deformatiOn of the filiform element''s cross-section thereby to widen said cross-section in a direction parallel to the edge of the tape and to impart to said protruding loops the required shape for them to act as hooking elements in a sliding clasp fastener.
 9. In a needle loom for manufacturing a tape having a list-thread provided with protruding loops and comprising means for separating the warp threads into two main sheets and for imparting to said sheets an alternate shed-forming movement, and a weft needle associated with a weft hook for inserting between said main sheets a weft thread in the form of double picks from a weft-thread insertion side, the improvement which comprises: means for forming an auxiliary sheet consisting of auxiliary warp threads superposed over at least a part, located to the weft-thread insertion side, of one of said main sheets and for compelling this auxiliary sheet to follow the shed-forming movement of this main sheet; an auxiliary needle for inserting, from the side opposite to the weft-thread insertion side, a list thread into the space between said auxiliary sheet and its associated main sheet, thus forming list-thread double picks; and means for retaining the heads of the list-thread double picks, said retaining means including a free needle disposed parallel to the tape side which is remote from the location at which the auxiliary needle enters said space, said free needle having a position with respect to the trajectory of the auxiliary needle such as to allow the heads of said list-thread double picks to entwine the free needle, thus being retained outside the tape in a transverse direction, and to slide longitudinally over the free needle while moving with the tape, said retaining means further including maintaining means able to hold the free needle in the same position before each entwinement by the list-thread double pick heads.
 10. The improvement defined in claim 9 wherein the free needle comprises a head located in alignment with the shed and a shank located in alignment with the tape, said shank having a smaller cross-section than that of the head and said head being connected to the shank by rounded surfaces.
 11. The improvement defined in claim 10 wherein said head has the form of a butt that is delimited, along the side remote from the tape, by a concave outline and, along the side adjacent the tape, by a rectilinear outline.
 12. The improvement defined in claim 10 wherein said head has the form of a ball secured at the end of said shank in an eccentric position in relation to the longitudinal axis of the shank, the offsetting being directed away from the tape.
 13. The improvement defined in claim 10 wherein said head has the form of a nose that is curved away from the tape.
 14. The improvement defined in claim 10 wherein said maintaining means include an abutment adapted to cooperate with said head so as to prevent it from rotating about its longitudinal axis and from being entrained longitudinally with the moving tape, thus holding said free needle in a given working position.
 15. The improvement defined in claim 14 wherein said abutment is a movable abutment wherein means is provided for imparting thereto a reciprocatory movement in a direction parallel to the motion of the tape, said reciprocatory movement including a withdrawal phase, in the direction of said motion, during which the abutment releases said head, and an advancement phase, in a direction opposite to said motion, during which the abutment returns the head to its initial position, the withdrawal phase beginning with the entwinement of the free needle head by the list-thread pick head and the advancement phase beginning after such entwinement.
 16. The improvement defined in claim 14 wherein said abutment is a stationary abutment endowed with the resiliency that is required to enable the head of the list-thread double pick inserted by the auxiliary needle to entwine the head of the free needle, by elastically moving the abutmeNt away from said head.
 17. The improvement defined in claim 10 wherein the shank of the free needle has the shape of a bevel, whose ridge is located to the side remote from the tape list.
 18. The improvement defined in claim 10 wherein the shank of the free needle has a cross-section of which the shape varies along said shank.
 19. The improvement defined in claim 10 wherein the shank of the free needle has a cross-section of which the area varies along said shank.
 20. The improvement defined in claim 19 wherein the variation of said area is continuous.
 21. The improvement defined in claim 19 wherein the variation of said area is discontinuous.
 22. The improvement defined in claim 9 wherein said maintaining means consists in a variation of the shape and area of said cross-section, said variation imparting to the free needle the shape of a sharp wedge having a slope so chosen that the free needle may be subjected, under the action of the tension in the list-thread, to a longitudinal force capable of compensating the driving force to which it is subjected under the effect of the tape motion.
 23. The improvement defined in claim 9, further comprising deforming means capable of producing, at the apexes of said list-thread double pick heads, a permanent deformation of the cross-section of the list thread, such deformation having the effect of broadening this cross-section in a direction parallel to the longitudinal axis of the tape whereby the tape may be utilizable as one of the halves of a sliding clasp fastener of which the hooking elements are formed by said protruding loops.
 24. The improvement defined in claim 23 wherein said deforming means include a crushing member having a slope adapted to cause progressive crushing of said list-thread double pick heads against the shank of said free needle while they slide along the shank.
 25. The improvement defined in claim 23 wherein said deforming means include a hammer adapted to crush said list-thread double pick heads against the shank of said free needle by hammering them while they slide along the shank.
 26. The improvement defined in claim 23 wherein said deforming means include a heating device capable of locally heating said list-thread double pick heads while they slide along the shank of said free needle.
 27. The improvement defined in claim 26 wherein said heating device includes a nozzle projecting a jet of hot air onto said list-thread double pick heads.
 28. The improvement defined in claim 23 wherein said deforming means include a generator of ultrasonic vibrations adapted to irradiate with ultrasonic waves said list-thread double pick heads while they slide along the shank of said free needle. 